How do polygraph tests work, and how accurate are they?
A polygraph machine, as the name implies, is simply a machine for recording many different bodily changes (sympathetic nervous system arousal)–not a lie detector. True, it does detect guilt… but the same thing could also be anger, pain, fear, or sexual arousal! Without going into the whole history of the thing, the false positive rate for a polygraph test can be as high as 60%. They are not accurate.
